In-vitro mineralization of bio-coated 3D printed metallic implant under simulated body conditions

Abstract

Titanium alloy, Ti6Al4V is a popular bio-metallic implant material due to its biocompatibility and inert nature. Further, by controlling the porosity of Ti6Al4V alloy through 3D printing not only helps it exhibit properties comparable to human bones, but also results in relatively rougher surface for improved coating adhesion. To induce bioactive characteristics in Ti6Al4V alloys, they are generally coated with Hydroxyapatite (HAp). In the present study in-vitro mineralization of polydopamine treated 3D printed Ti6Al4V alloy specimen, which are HAp coated and further doped with strontium and silver nitrate for improved bioactivity and anti-microbial characteristics respectively, is carried out for a maximum of 28 days’ time duration. These coated specimens are then characterized through Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) for microstructural analysis, and further evaluated for weight gain and coating thickness. SEM data suggests a consistent apatite formation over a period of time across the different coating groups. Although the samples containing Sr & Ag were initially showing lower Ca & P atomic % in range of 50 and 29 respectively, but there is a substantial increase in atomic percentages of both Ca and P to 66 & 33% respectively, completely covering the Ti surface homogeneously as evidenced by elemental mapping results after 28 days’ time duration. This study is helpful to understand the phenomenon of apatite formation over the period of time on different biofunctional coatings when compared to pure HAp coatings.